Package-on-Package Wire Stick Interconnects for Reduced Profile
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces limitations in reducing the total thickness of package-on-package (PoP) technology due to the restricted solder ball joint height between the top and bottom packages, which hinders further integration density and miniaturization of electronic components.
Innovation Solution
The use of wire sticks, formed by cutting and bonding conductive wires to bond pads on a substrate, provides separation, support, and electrical connectivity between packages, allowing for controlled solder joint height and size, enabling a lower profile and increased integration density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If solder ball joints are used to connect top and bottom packages in PoP technology, then electrical connectivity is achieved, but the total package thickness cannot be reduced further due to limited solder ball joint height
Solution Approach 1:
The patent changes the physical parameters of the connection structure by replacing spherical solder balls with wire sticks that have controllable length and diameter. This allows independent optimization of connection height and mechanical strength, resolving the limitation where solder ball diameter directly determined both connection strength and minimum package thickness.
Solution Approach 2:
The patent employs wire sticks as temporary structural elements during assembly that can be precisely controlled in length and then embedded in solder joints. This approach allows for optimized connection geometry without the constraints of permanent solder ball dimensions, enabling thinner package profiles while maintaining reliability.
2Area of stationary object
If smaller packages are used to increase integration density, then area is reduced, but manufacturing precision and assembly yield become more difficult to maintain
Solution Approach 1:
The patent applies wire sticks to the substrate with OSP layers before final soldering, establishing precise positional relationships in advance. This preliminary positioning ensures accurate alignment in small packages, maintaining assembly yield despite reduced package area and tighter tolerances.
Solution Approach 2:
The wire sticks serve as intermediary elements between the substrate and final solder connections. They provide a controllable, precise interface that facilitates accurate assembly in miniaturized packages, acting as a buffer that maintains manufacturing precision even as package dimensions decrease.
3Length of stationary object
If wire sticks are used instead of solder balls, then solder joint height can be controlled and package profile reduced, but new manufacturing processes are required
Solution Approach 1:
The wire sticks are designed to be self-aligning and self-positioning on the substrate with OSP layers. Their geometry and bonding characteristics enable automatic placement and alignment during assembly, reducing the need for complex positioning equipment and processes despite the novel material form.
Data Source
AI summary
An embodiment is a package-on-package (PoP) device comprising a first package on a first substrate and a second package over the first package. A plurality of wire sticks disposed between the first package and the second package and the plurality of wire sticks couple the first package to the second package. Each of the plurality of wire sticks comprise a conductive wire of a first height affixed to a bond pad on the first substrate and each of the plurality of wire sticks is embedded in a solder joint.